Generally, in a vent-type extruder, deairation is effected by reducing the pressure applied on the resin when the material resin is subjected to a melting process. In this case, it is usual to provide a deairing port between the compression zone and melting zone of the extruder.
However, in a device for treating synthetic resin waste of the type utilizing internal heat due to a thermal action produced in crushing of the synthetic resin waste or shearing of the particles of synthetic resin, it is impossible to execute lowering of the pressure or deairation in the melting process of the synthetic resin waste.
With a device for treating synthetic resin waste in which the thermoplastic resin is melted utilizing friction heat as described before, it is impossible to melt the thermoplastic synthetic resin itself in the waste if the pressure and the temperature are lowered in the course of melting. That is why volatile matter could not be driven off from the above device which cannot carry out extrusion under a high temperature and a high pressure.
In the present invention, an apparatus for treating synthetic resin waste is made by combining a "deairing and back-pressure increasing mechanism" and a device of the type utilizing friction heat as stated before and also as described in U.S. Pat. No. 3,783,567. By using the apparatus it is possible to drive off volatile matter from the melt of synthetic resin waste containing thermoplastic synthetic resin and also to carry out extrusion under a high pressure. Consequently it is possible to obtain a product which has an excellent mechanical strength and good quality and having no voids internally.
The present invention relates to an apparatus for treating synthetic resin waste utilizing friction heat produced by crushing of the synthetic resin waste or shearing of the particles of the synthetic resin, etc.
In general, various substances are contained in synthetic resin waste material. They are, for example, sand, gravel, paper, etc. This foreign matter often contains water, or other volatile matter.
Therefore, when the synthetic resin waste containing the various foreign matter are melted and extruded, the volatile matter in the foreign matter forms vacant spaces in the product and products molded with the melt as the molding material form internally with faults due to air bubbles, etc.
Accordingly, in the present invention, the apparatus is supplemented by a "deairing and back-pressure increasing mechanism" provided on the body of a melting and extruding device to drive off the volatile matter contained in the melt. The products made of such a melted material assure excellent quality without internal faults.